One legend for all subplots in pyplot

Question

I am currently plotting the same data but visualizing it differently in two subplots (see figure):

Code snippet used for producing the above figure:

# Figure
plt.figure(figsize=(14,8), dpi=72)
plt.gcf().suptitle(r'Difference between TI and $\lambda$D', size=16)
# Subplot 1
ax1 = plt.subplot2grid((1,3),(0,0),colspan=2)

# Plot scattered data in first subplot
plt.scatter(LE_x, LE_y, s=40, lw=0, color='gold', marker='o', label=r'$\lambda$D')
plt.scatter(MD_x, MD_y, s=40, lw=0, color='blue', marker='^', label=r'TI')

# Subplot 2
ax2 = plt.subplot2grid((1,3),(0,2))

plt.barh(vpos1, LE_hist, height=4, color='gold', label=r'$\lambda$D')
plt.barh(vpos2, MD_hist, height=4, color='blue', label=r'TI')

# Legend
legend = plt.legend()

Is there any way to make the legend show both the scatter dots and the bars? Would this also go per dummy as described here? Could somebody then please post a minimal working example for this, since I'm not able to wrap my head around this.

Solution

This worked for me, you essentially capture the patch handles for each graph plotted and manually create a legend at the end.

import pylab as plt
import numpy as NP

plt.figure(figsize=(14,8), dpi=72)
plt.gcf().suptitle(r'Difference between TI and $\lambda$D', size=16)
# Subplot 1
ax1 = plt.subplot2grid((1,3),(0,0),colspan=2)
N = 100
LE_x = NP.random.rand(N)
LE_y = NP.random.rand(N)
MD_x = NP.random.rand(N)
MD_y = NP.random.rand(N)

# Plot scattered data in first subplot
s1 = plt.scatter(LE_x, LE_y, s=40, lw=0, color='gold', marker='o', label=r'$\lambda$D')
s2 = plt.scatter(MD_x, MD_y, s=40, lw=0, color='blue', marker='^', label=r'TI')

data = NP.random.randn(1000)
LE_hist, bins2 = NP.histogram(data, 50)

data = NP.random.randn(1000)
MD_hist, bins2 = NP.histogram(data, 50)
# Subplot 2
ax2 = plt.subplot2grid((1,3),(0,2))
vpos1 = NP.arange(0, len(LE_hist))
vpos2 = NP.arange(0, len(MD_hist)) + 0.5
h1 = plt.barh(vpos1, LE_hist, height=0.5, color='gold', label=r'$\lambda$D')
h2 = plt.barh(vpos2, MD_hist, height=0.5, color='blue', label=r'TI')

# Legend
#legend = plt.legend()
lgd = plt.legend((s1, s2, h1, h2), (r'$\lambda$D', r'TI', r'$\lambda$D', r'TI'), loc='upper center')
plt.show()